So you want to grow a Giant pumpkin? Well the time to prepare starts now. First decide where you are going to grow your pumpkin. (It will need a lot of space- most recommend 400 square feet or more). Work up the soil and add lots of organic matter such as composted cow manure, peat moss and compost. Next, test the pH of the soil. Adjust it until it is between 6.5 - 6.8. You can raise pH by adding lime. If it needs lowered you can do this with sulfur. Some pumpkin growers like to have a winter cover crop of rye that is tilled into the soil in the spring.